The present invention relates generally to an image processing apparatus for obtaining image data by photoelectrically reading an image on a film, executing predetermined image processing upon the obtained image data, and thus obtaining the image data for output, and more particularly to an image processing apparatus based on a technology of compensating a drop (decrease) in light quantity in the periphery of the image which occurs with respect to the image photographed on a one time use camera, etc.
A prevailing method of printing on a photosensitive material (photographic printing paper) an image photographed on a photographic film such as a negative film and a reversal film (which are hereinafter generically referred to as a film), has hitherto been a so-called direct exposure (analog exposure) of exposing a surface of the photosensitive material to the light by projecting the film image upon the photosensitive material.
By contrast, there has been in recent years utilized a printing apparatus that makes use of a digital exposure, i.e., a digital photo printer for obtaining a (finished) print by photoelectrically reading an image recorded on the film, converting the read image into digital signals, thereafter executing a variety of image processing on the digital signals to thereby acquire image data for record, and recording the image (latent image) by scan-exposing the photosensitive material to a recording light beam modulated corresponding to the above image data.
The digital photo printer is capable of converting the image into digital image data and determining an exposure condition when in printing through the image data processing, and is therefore able to obtain a high quality print, which could not be acquired so far by the prior art direct exposure method, by preferably compensating a discontinuous density and an over-density (such as a washed-out highlight and a dull shadow) of the image which might be attributed to back light and electronic flash photography, etc., executing a sharpness (sharpening) process, and compensating a failure in terms of color or density. The digital photo print is also capable of synthesizing a plurality of images or dividing the image as well as synthesizing characters by the image data processing, and outputting a print which is edited and processed flexibly corresponding to applications.
Besides, the digital photo printer is capable of supplying the image data to a comouter, etc. as well as outputting the image by way of a print and storing a recording medium such as a floppy disk, etc. with the image data, and the stored data can be therefore utilized for a variety of applications other than the photography.
This type of digital photo printer is constructed basically of an image input apparatus including a scanner (image reading apparatus) for photoelectrically reading the image recorded on the film and an image processing apparatus for executing image processing on the read image to obtain image data (exposure condition) for output, and an image output apparatus including a printer (image recording apparatus) for recording a latent image by scan-exposing the photosensitive material to the light in accordance with the image data outputted from the image input apparatus, a processor (developing apparatus) for obtaining a print by executing a developing process on the exposed photosensitive material.
In the scanner, reading light beam emitted from a light source is incident on the film, projection light bearing an image photographed on the film is thus obtained and projected to form the image at an image sensor such as CCD sensors through an image-forming lens, the image is read by performing a photoelectric conversion, and the image is subjected to various processes according to the necessity and is thereafter transmitted as image data (image data signals) of the film to the image processing apparatus.
The image processing apparatus sets an image processing condition based on the image data read by the scanner, executes the image processing corresponding to the set condition upon the image data, and sends the data as output image data (exposure condition) for recording the image to the printer.
The printer, if classified as an apparatus utilizing, e.g., a light beam scan exposure, modulates the light beam corresponding to the image data transmitted from the image processing apparatus, deflects the light beam in a main scan direction, then carries the photosensitive material in a auxiliary scan direction orthogonal to the main scan direction, forms a latent image by exposing (printing) the photosensitive material to the light beam carrying the image, and subsequently executes a developing process corresponding to the photosensitive material in the processor, thereby obtaining the print (photo) containing the reproduced image photographed on the film.
It is preferable for obtaining the high quality print that the possibly greatest number of images (image information) of photographed scenes be recorded on the film with fidelity.
In particular, however, a so-called one time use camera integrated with a lens and a film is unable to enhance a lens performance so much because of its being severely restricted in terms of cost, with the result that a marginal light quantity about the image center decreases. The one time use camera is also called a single use camera, lens with film or snap shooting unit. As a consequence, there arises a problem that the area peripheral to the image is darkened in the finished print.
Accordingly, it is a primary object of the present invention, which was devised to obviate the problems described above, to provide an image processing apparatus capable of compensating a decrease in light quantity of an area peripheral to the image even when the image is photographed through a low-performance lens, and obtaining a high quality image with stability without any darkened peripheral area.
To accomplish the above object, according to one aspect of the present invention, there is provided an image processing apparatus for executing predetermined image processing on image data obtained by photoelectrically reading an image photographed on a photographic film through a photographic lens of a camera, and thus obtaining the image data for output. The image processing apparatus comprises a unit for obtaining a characteristic of the photographic lens, a unit for developing the characteristic of the photographic lens into a dipping quantity corresponding to a position of the image, and a unit for compensating a marginal light quantity of the image by use of the dipping quantity.
In the thus constructed image processing apparatus, it is preferable that the marginal light quantity compensating unit changes an intensity of the marginal light quantity compensation corresponding to a film density of the image, decreases the compensation intensity in the vicinity of a minimum density on a film (e.g., a base density implying an unexposed area on a negative film, and a density defined as the fog area in a reversal film) or a maximum density in the film (e.g., a density defined as the fog area in a negative film, and a base density implying an unexposed area in a reversal film), and increases the compensation intensity as it gets farther away from the minimum density or the maximum density.
The image processing apparatus may further comprise a manes for obtaining information on the photographic film, and a means for converting the film density into a photographic light quantity and vice versa by use of a characteristic of the photographic film which is obtained from the information on the photographic film. It is preferable that the marginal light quantity be compensated in a range of the photographic light quantity.
It is also preferable the marginal light quantity compensating means executes, when in a pre-scan process of reading the image with a low resolution in advance of an image reading process for creating the output image data, the marginal light quantity compensation before an image analyzing process containing an auto setup process, or after making only an adjustment of a color balance in the image analyzing process.
It is further preferable that an image processing apparatus further comprises the means for obtaining information on said photographic lens, and a table previously created for showing a relationship between the information of the photographic lens and the characteristic of the photographic lens, wherein said photographic lens characteristic obtaining means reads a characteristic of said photographic lens corresponding to the obtained information of the photographic lens from the photographic lens information obtaining means and the table.
It is still further preferable that the marginal light quantity compensating means compensates a marginal light quantity of the image by use of a distance from a center of the image and the dipping quantity.
It is yet further preferable that the means for developing the photographic lens characteristic into the dipping quantity is a means for calculating a dipping quantity corresponding to the distance from the center of the image in accordance with the photographic lens characteristic.
In addition, it is preferable that the marginal light quantity compensating means does not compensate so much the marginal light quantity in the vicinity of the minimum density or the maximum density with respect to the image, intensively compensates the marginal light quantity in a density range existing away from the minimum density or the maximum density, and intermediately compensates the marginal light quantity in an intermediate density range therebetween.